I really need some help/advice on this one...

[Maverick223]

Anyone know the rated pressure limit of a 450 Nitro Express 3.25"...it just so happens to have the EXACT same internal case dimensions of the .45-120. It would give me a great place to work up to, as 450NE loads are available, though difficult to find. It seems that RL-15 and N560 are good powders to start with, and 4831 (both IMR and Hod.) may be a good load, as I already use it for my .300WM.

 

[Maverick223]

BUMP for any further comments/advice/words of wisdom. Anyone know the pressure of the old 450 Nitro Express 3.25"?

 

[fireman 9731]

From Wikipedia:

Early cartridges used the black powder case that was designed for around 11 tons of pressure per square inch and not the 17 tons of pressure that the Cordite load generated. Case extraction was difficult, especially in warmer climates such as Africa and India where the cartridge was primarily used. To remedy this problem, a reinforced case was produced and Kynoch made a reduced load to lower the case pressure.

So around 22,000 PSI for black powder and 34,000 PSI for the Cordite load.

That might be rough ballpark area to start with... I couldn't find much else.

 

[Maverick223]

That might be rough ballpark area to start with... I couldn't find much else.

Thanks fireman...I'd rather have a better source, but beggars can't be choosers, and that is better than what I didn't find. At least that confirms what I thought...that even the later nitro rounds were less pressure than what the 1885 High Wall is rated for (50,000CUP Max, 40,000CUP Working Pressure according to SAAMI IIRC). I still plan to work up to it, and will keep it well below 40,000CUP, but it is nice to have a idea of where I will end up at with my pressure and velocity.